Objective: The incidence of post-operative adhesions is estimated to be 93%, resulting in severe pain, bowel obstruction, infertility, and often requires re-operation. Mainstay adhesion prevention technologies are generally derived from polymer films that serve as physical barriers between scarring tissue and surrounding organs. Yet, these films have not been widely accepted due to their inability to adequately limit adhesions and difficulty handling during surgery. We hypothesized shear-thinning, self-healing polymer nanoparticle hydrogels (PNP) would instead provide a novel, viscoelastic barrier between tissues and organs, allowing tissues to move past each other similar to the body’s natural state, effectively preventing adhesion formation (Fig. 1A).
Methods: PNP shear-thinning and self-healing behavior was characterized via rheometry. Adult male Sprague Dawley rats (n=23) underwent sham surgery or permanent ligation of the LAD followed by pericardial application of 250μL PNP gel, 1cm2 Interceed®--a commercially available adhesion barrier, or no treatment. Degree of adhesion formation, cardiac function, infarct size, and immune response were assessed 4-weeks post infarction.
Results: PNP exhibited fast, complete recovery of mechanical properties following network rupture at high strains indicating the reversible and robust nature of the hydrogel system. (Fig. 1B). Infarct size and ejection fraction were controlled to ensure similar inflammatory responses contributing to adhesion formation across treatment groups (1C and D). Treatment with PNP significantly reduced the development of adhesions compared to Interceed and untreated controls (Fig. 1E).
Conclusion: Administration of a shear-thinning, self-healing hydrogel reduces the extent of adhesion formation in the thoracic cavity following a thoracotomy and myocardial infarction. PNP provides an easily delivered, scalable solution for post-operative adhesion prevention.